I'd be glad to provide some information about the QBXML format.
Since we can only export transactions as Excel or PDF in QuickBooks Online (QBO), I recommend searching for third-party applications that integrate with the program. Just go to the Appsmenu or through the external QuickBooks App Center.
Here's how:
Go to the Apps menu.
Type a keyword in the search field. You can also click the Browse category to narrow down the results.
Select the app to open its profile. View the other apps by clicking them.